12 THE MARIXE ALG.E OF GUERNSEY 



DiCTTOTE.E. 



DiCTTOTA DICHOTOMA Lamour. c. W. 7. — var. implexa 

 J. Ag. (var. intricaia Ag.). [E. 2. S. 2, 3.] W. 1. 



Padixa Payonia aaillon. [W. 4. N.W.3, 4.] N. 2. N.W. 2. 



DiCTY'OPTERis MEMBRAis^ACEA Batt. {Haliserls 2^olypodioides 

 Ag.). [E.IO. Kl.] S.W.andE.ll. Dredged and in deep 

 rock-pools. 



FLORIDE^, 



PORPHYRE^, 



€.1, GoNiOTRiCHUM ELEQANS Le Jol. {Bcingia elegans Cliauv.) E.G. 

 v.r. 



Erythrotrichia carnea J. Ag. {Bang la ceramicola Cliauv.). 

 E. 11. on Ce7\ ciliatuDu] On Rho. Hotliii. 

 e. E. REFLEXA Thur. {Bangia rejiexa Crn.). W. 1. v.r. 



E. Welwitschti Batt. v.r. H. &. B. 



Bangia euscopurpurea Lyngb. Batters, w 

 G. PoRPHYRA leucosticta Tliur, N. 2. E, 6. N. W. 3. 



P. LINEARIS Grev. (P. vulgaris Harv.). E. 6. 



P. UMBiLiCALis Kiitz. — var. laciniata J. Ag. c. — var, unibili- 

 €alis J. Ag. c. 



The markedly scanty distribution of this species along the 

 exposed and moderately exposed coasts of Guernsey during the 

 summer and autumn months may be accounted for by the 

 fact that Porphyra is said to be a winter and spring plant in 

 the South of England. On the other hand, luxuriant growths 

 in very sheltered conditions persisted through the summer 

 and still flourished in November. There were also quite 

 appreciable quantities in even moderately sheltered districts. 



P. umhilicalis hangs down from the rocks and boulders, 

 giving place to P. laciniata where there is shelter, on low 

 rocks often half buried in the sand. Intermediate stages 

 between the two forms show the relationship distinctly. 

 Along the thallus little holes or slits apj^ear, wliich by their 

 extension lengthwise, cause the S23litting up into the laciniate 

 form. These transitions would seem to indicate that var. 

 laciniata is developed from P. umhilicalis, iwssibly as a result 

 of mechanical agencies, such as sand-friction and wave-action. 



EUFLORIDEiE. 



Chantransia Schm. {Achrochcetium Nag.), 



These generic names were used by Bornet to designate the 

 -sexual and asexual conditions. As further research has shown 

 the presence of sexual organs in an increasing number of 

 species, Rosenvinge has united them all under Chantransia. 

 <o. Chantr.ansia virgatula Thur. E. 2. — var. luxurians Nag. 

 [E. 12.]. E. 6. On a limpet-shell. — (g.) var. secundata 

 Eosenv. E. 7. On other alga3. 

 CM, C. CORYMBIFERA Thur. (Achrockcetium corymhiferum Batt.). 

 E. 11. N.W. 3. On Cer. ruhrum and other algae. 



